This was a list I developed in the summer as I thought indexes were likely at a major high area. I've edited it slightly for clarity.

Sum
Several conditions exist - most especially multiple USA main indexes on long term resistance, RSI extremes and weekly & monthly Bollinger bands, and sentiment. But until we see VIX and XIV confirming trouble, mostly likely scenario is small dips that are bought as market settles into sideways digestion period.

1 - Pivots
A. Multiple major USA indexes at major resistance?
B. Rejections from those levels?
C. VIX / XIV alert?
D. Other global indexes already weaker?

1A check! 1B partially, 1C not yet - not at all.
1D, a new consideration - mixed here with developed markets NKY & DAX fine with higher highs on 12/16. But emerging markets especially China and India having trouble.

2 - Other Technicals
A. RSI extreme reached?
B. Negative divergence?
C. Bollinger bands in play, or divergence?
2A yes quite; 2B, starting recently; 2C yes on several weekly and monthly charts.

3 - Price action
High tested with at least one lower high?
No. OK, on short timeframes 12/15 could be considered a test / lower high from 12/13 but this is not what I mean. I mean more like summer topping process with initial high 8/15, test 8/23, then lower highs 9/7.

4 - Safe havens showing concern?
TLT no, GLD above YP would add to stock drop possibility.

5 - Breadth or volume divergence?
Declining stock volume has made a fast trip back to negative territory. Bit odd to see higher high then fast lower low.

6 - Sentiment extremes reached?
Yes definitely, per this post on 12/11.

7 - Valuation level?
Enough, but more powerful on a full round number. SPX currently near 17.5x forward earnings. 17 down near 2215 and 18x at 2345.

8 - Timing?
Did not have 12/13 area listed.